When a stage lamp is used, if a light filter thereof is used near a light source, the light filter will reflect a lot of light energy, and a part of the light energy reflected from the light filter and a part of the light energy emitted by the light source are converged on an electrode at an upper end of a lamp post at a central position of a lamp. Especially when the light filter is perpendicular to a light axis, more light energy will be converged on the electrode, thus causing that a temperature of the electrode increases sharply, while an excessively high temperature will seriously shorten a service life of the lamp electrode, thus accelerating the failure of the lamp. Therefore, how to reduce the temperature of the lamp electrode under the premise of ensuring an ideal optical effect of the lamp has become an important research topic in the thermal design of stage lighting.
According to the existing lamp thermal control technologies, in order to make the part of the light energy reflected from the light filter no longer pass through a lamp post electrode, a light filter with a certain included angle is used, so that a temperature of the lamp post electrode is controlled not to exceed a standard, and the service life of the lamp electrode is ensured. However, the light filter with an included angle can cause uneven light color projected by the lamp, so that an ideal optical effect of a flat light filter without an included angle cannot be realized.